This is the second column I’ve written about Deborah Loewenberg Ball, the dean of the University of Michigan School of Education. Ball believes the training that teachers get while they are in school needs to be drastically improved. Last year, I wrote about her effort to develop a professional training curriculum that would allow beginning teachers to be far better grounded in their craft than they are now.

Recently, I learned about another effort she has led, which I also think deserves wider attention. It tackles one of the most divisive topics in K-12 education: how to evaluate teachers so that the best can be rewarded and the worst fired.

In New York — a state where the issue has been especially contentious — Gov. Andrew Cuomo earlier this year pushed through legislation that calls for student test scores to count for as much as 50 percent of a teacher’s evaluation, up from the current 20 percent. The teachers’ unions were incensed, believing that test scores are a simplistic and unfair means of assessing teachers. So were many parents, who joined a boycott movement that resulted in an estimated 165,000 students opting out of this year’s standardized tests.

A teacher evaluation system “is only good if the teachers respect it and trust it,” says Vicki Phillips, a director of education for the Bill & Melinda Gates Foundation. Teachers are convinced that evaluation systems that overly rely on test scores are punitive, which the political rhetoric often underscores. For instance, Cuomo’s stated reason for changing the state’s teacher evaluation was that some 96 percent of teachers got top grades under the old process. He scoffed at those results as “baloney.” That’s hardly going to get teachers to buy into your new evaluation system.

Which brings me back to Michigan. In 2011, the State Legislature there changed the tenure law, making it easier to fire incompetent teachers. But it also set up the Michigan Council for Educator Effectiveness, which was charged with coming up with its first-ever statewide evaluation system. Ball was named chairwoman of the council. Two years later, it came back with its recommendations.

The first thing I noticed about the council’s recommendations is that they completely avoid the divisive political language that has alienated teachers. Instead of casting teacher evaluation as primarily being about getting rid of bad teachers, they put the emphasis on teacher improvement. An evaluation system that stresses improvement instead of punishment has a much better chance of being embraced by teachers.

Such an emphasis isn’t just good politics. It’s also an important way to help make schools better. “Very few teachers can’t improve,” Ball told me recently. And most teachers want to improve — but have no means of getting useful feedback. The council’s idea was that the evaluations could be used not just to rid the system of incompetent teachers — though it would certainly do that — but also to give all the other teachers critical feedback. It also envisions transforming professional development, which is now mostly a wasteland, into a mechanism to put that feedback into practice.

There are two fundamental pieces to the Michigan council’s plan. The first piece is teacher observation. In most schools, it’s the principal who observes the teacher, often haphazardly, and rates him or her based on personal biases, which may or may not be sound. Ball and her colleagues would instead rely on observers who have been trained in using certain tools that have been proved effective. These observations would be the basis for the teacher’s feedback . feedback meant to encourage and help, rather than threaten.

The second piece is what the council calls evaluating “student growth.” Here the point would be not to measure student achievement in absolute terms — Does Johnny read at a fourth-grade level? — but rather to measure whether Johnny had made a year’s worth of improvement from the level he was reading at when he was in the third grade. This would be a more accurate representation of the difference the teacher made, and would take into account the wide range of learning levels teachers often have to contend with.

Some of this growth evaluation would undoubtedly be done through tests. But not all of it, or even most of it. “You have to look at objectives for students for the year and see if they made progress,” says Ball. There are ways to do that that don’t require standardized testing.

I wish I could tell you that this story has a happy ending, but it doesn’t. Legislation that embodied the work of the council failed to pass the Michigan Legislature in the last session. More recently, the chairman of a related Senate committee, Phil Pavlov, has essentially tossed the council’s work aside in favor of “local control.”

That is Michigan’s loss. But perhaps other states and school districts can look at the work of the Michigan council and learn from it. In which case, it could still be America’s gain.